This invention relates to tools used in the heavy truck brake repair industry and, more particularly, to such a tool which is used to facilitate the attachment and removal of the springs which are anchored to and bias a set of brake shoes in a direction toward each other.
Large vehicles such as heavy trucks and buses, for example, utilize air-brake systems which employ a pair of arcuate brake shoes for each wheel axle. Upon actuation of the braking system, the brake shoes are forced outwardly whereby the brake shoe linings frictionally engage the drum to cease rotation of it's associated wheel to slow and/or stop the vehicle. In the usual break arrangement, the brake shoes are positioned opposite each other with the linings thereof facing outwardly toward the drum. The shoes are mounted about a backing plate and include a set of helical springs biasing the shoes toward each other in a direction away from the drum.
The present day method of anchoring the springs to the shoes requires awkward and strenuous manual manipulation of the shoes about the springs to achieve proper positioning thereof about the backing plate. Without the aid of any tools, the worker must be able to anchor the springs to each brake shoe which requires movement of at least one of the shoes in a direction against the biasing force of the springs. This movement, if done improperly, has been known to tension the springs beyond their elastic limit which would thereafter require replacement.
In the "S cam" type of air-brake presently manufactured by Rockwell International under the trademark THE ROCKWELL Q FLUS, each brake shoe must be equipped with rollers which bear against an S-shaped cam positioned therebetween. When the braking system is actuated, the cam rotates thereby forcing the brake shoes against the drum as the rollers ride along the cam as will be understood more fully in the Detailed Description. Installation of the roller between each shoe and the ca requires the worker to force the shoe away from the cam to provide clearance for insertion of the roller (with the springs already in place). To accomplish this, the worker usually utilizes a crow-bar to insert between the brake shoe and the cam to pry them apart a distance permitting insertion of a roller therebetween. Thus, while one hand is holding the crow-bar in the position separating the shoe from the cam, the worker must use his other hand to insert the roller therebetween. A major hazard to the worker is the possibility of slippage of the crow-bar while installing the roller which could catch the worker's hand between the shoe and the cam.
Due to the above-mentioned difficulties of installing the shoes, spring and rollers of a brake, including the hazards associated therewith, the present invention is aimed towards providing a tool with which to install the springs upon a set of brake shoes.
It is therefore a main object of the present invention to provide a tool which greatly facilitates the installation of the springs upon a set of brake shoes.
It is a further object to provide a tool which reduces the amount of time required to install the springs upon a pair of brake shoes.
It is another object to provide a hand operated tool which substantially decreases the threat of injury to the user during use of the tool to install or remove the springs anchored between a pair of brake shoes.
Yet another object of the invention is to provide a tool having the above-mentioned characteristics which is simple in design, easy to use, cheap to manufacture, and which is otherwise economically attractive.
Other objects will in part be obvious and in part appear hereinafter.